1. Field of the Invention
The present invention relates to a method of manufacturing an electronic component built-in substrate and, more particularly, a method of manufacturing an electronic component built-in substrate in which a passive component, a semiconductor chip, or the like is mounted to be embedded in an insulating layer.
2. Description of the Related Art
In the prior art, there is the electronic component built-in substrate in which the electronic component such as the capacitor, or the like is mounted to be embedded in the insulating layer. As a first method of manufacturing an electronic component built-in substrate in the prior art, as shown in FIG. 1A, first, a core substrate 100 in which a wiring layer 140 is provided to both surface sides respectively is prepared. Through holes TH are provided in the core substrate 100, and a through electrode 120 is provided in the through holes TH respectively. The wiring layers 140 on both surface sides of the core substrate 100 are connected mutually via the through electrodes 120.
Then, as shown in FIG. 1B, a capacitor component 200 having connection electrodes 220 on both end sides is prepared. The connection electrodes 220 on both end sides of the capacitor component 200 are connected to the wiring layer 140 on the upper surface side of the core substrate 100 with solder 240.
Then, as shown in FIG. 1C, an insulating spacer 300 in which an opening portion 320 whose area is one size larger than an area of the capacitor component 200 is provided and whose thickness corresponds to a thickness of the capacitor component 200 is prepared. The insulating spacer 300 is secured on the core substrate 100 such that the capacitor component 200 is arranged in the opening portion 320. Thus, a level difference of the capacitor component 200 is almost eliminated by a thickness of the insulating spacer 300.
Then, as shown in FIG. 1D, a semi-cured resin film 400 is bonded by pressure on the capacitor component 200 and the insulating spacer 300. Then, as shown in FIG. 1E, the semi-cured resin film 400 is cured by the heat treatment while causing to flow, and thus an interlayer insulating layer 500 formed by the insulating spacer 300 and the resin film 400 is obtained. Accordingly, the whole of the capacitor component 200 is embedded in the interlayer insulating layer 500.
As a second method of manufacturing an electronic component built-in substrate in the prior art, as shown in FIG. 2A, the connection electrodes 220 of the capacitor component 200 are connected to the wiring layer 140 on the core substrate 100 with solder 240, like FIG. 1A. Then, as shown in FIG. 2B, a semi-cured resin film 420 is bonded by pressure on the capacitor component 200, and thus the capacitor component 200 is embedded in the semi-cured resin film 420. Then, as shown in FIG. 2C, the resin film 420 is cured by the heat treatment, and thus the interlayer insulating layer 500 in which the whole of the capacitor component 200 is embedded is obtained.
As the technology related with the above prior art, in Patent Literature 1 (Patent Application Publication (KOKAI) 2007-116155), it is set forth that, in the method of manufacturing the electronic component built-in substrate, a warp of the substrate is prevented by mounting the molded passive component into the cavity formed in the substrate.
Also, in Patent Literature 2 (Patent Application Publication (KOKAI) 2005-302854), it is set forth that the through hole is formed to pass through an insulating layer on one surface of which the copper foil is pasted and on other surface of which the adhesive layer is provided, then the electronic component to both ends of which the solder terminal portions are provided is inserted into the through hole, and then the copper foil is pasted to the adhesive layer, whereby the component built-in both sides substrate in which the interlayer connection is achieved via the electronic component is obtained.
In the above first method of manufacturing an electronic component built-in substrate in the prior art (FIGS. 1A to 1E), in order to eliminate a level difference of the capacitor component 200, the insulating spacer 300 in which the opening portion 320 is formed by the machining must be prepared in advance. Therefore, the number of man-hours in processes is increased. Also, when an adhering function should be provided to the insulating spacer 300, the semi-cured resin film must be used as the insulating spacer 300. But it is difficult to form the opening portion in the semi-cured resin film by the machining. Therefore, such approach cannot be easily applied to various processes.
Further, the opening portion 320 in the insulating spacer 300 must be aligned with the capacitor component 200. Therefore, when particularly the capacitor component should be reduced in size, it is extremely difficult to align them mutually with good accuracy.
Also, in the above first method of manufacturing an electronic component built-in substrate in the prior art (FIGS. 2A to 2C), at a time the interlayer insulating layer 500 is obtained by embedding the capacitor component 200 in the semi-cured resin film 420, it is difficult to eliminate sufficiently a level difference of the capacitor component 200. In many cases, a level difference still remains on the upper surface of the interlayer insulating layer 500. Therefore, at a time the wiring layer is formed on the interlayer insulating layer 500, it is difficult to form the wiring layer with good accuracy. Also, such a problem exists that a warp is ready to occur due to a different in a coefficient of thermal expansion between the core substrate 100 and the interlayer insulating layer 500, and others.